1. Industrial Field of the Invention
The present invention relates to an apparatus for cake removal in a filter press of the type in which filter plates are adapted to be simultaneously separated from one another.
2. Prior Art
In the operation of a filter press, filtration is carried out when all filter plates are in a tightly assembled condition, and when cake has been accumulated in filter chambers after a predetermined period of filtration, it is necessary that supply of the liquid to be filtered be suspended for a while to enable the filter plates to be separated one from another for removal of the cake.
Therefore, according to the manner in which the filter plates are separated for the purpose of cake removal, filter presses may be broadly classified into two types, namely, the so-called simultaneous plate separation type in which individual filter plates entrained between a pair of clamping heads are simultaneously separated one from another for cake removal, and the so-called sequential plate separation type in which filter plates arranged between a pair of clamping heads are sequentially separated and assembled one by one, or by twos or more, so that each time adjacent filter plates are separated from each other, the cake accumulated between the filter plates are removed.
Conventional filter presses of the simultaneous plate separation type, in which the filter plates cannot be separated so wide apart from one another, are of such arrangement that when all the filter plates are simultaneously separated, filter cloths are caused to run simultaneously so that cakes depositing on individual filter cloths are conducted outward together with the filter cloths from spaces between individual pairs of adjacent filter plates for simultaneous removal of the cakes. In conventional filter presses of the sequential plate separation type, individual pairs of adjacent filter plates can be separated enough to give wide intervals therebetween and, accordingly, as they are sequentially separated, vibration is applied to each filter cloth between the adjacent filter plates separated, cake being thereby removed from the filter cloth.
3. Problems to be Solved
With conventional filter presses of the simultaneous plate separation type, therefore, it can be pointed out that since cake removal can be carried out on a simultaneous operation basis, they are advantageous in that a cake removal operation can be completed in a short time, on one hand, while on the other hand they have an inherent shortcoming that a cake removal apparatus employed therein involves a relatively high cost of manufacture. Conventional filter presses of the sequential plate separation type have an advantage that the provision of a cake removal apparatus for use therein involves less cost of manufacture, but on the other hand they are disadvantageous in that a longer period of operation is required for cake removal.
In the art of filter press, in order to enable accurate separation from filter cloth surfaces of cakes which are rather difficult to remove, if such cake is produced in the course of filtering operation, it has been customary to employ cake removal means of the filter cloth travelling type, as in simultaneous separation type filter presses in which, when the filter plates are separated, an interval provided between adjacent filter plates is rather small; and in the case of filter presses in which cake removal means of the filter cloth jolting type are used, it has been customary to employ a filter plate open/close arrangement of the sequential separation type in order to provide sufficient intervals between individual pairs of adjacent filter plates. However, the characteristics of the liquid to be filtered by any filter press may vary according to the site at which the filter press is employed; and not all liquids to be filtered are hard to filter, and not all cakes resulting from filtration are hard to be removed from filter cloth surfaces.
Therefore, where the liquid to be filtered is highly filterable, as in the case of ore-containing sludge, for example, and the resulting cake is so easily separable from filter cloth surfaces that when the filter plates are separated, a larger part of the cake produced is likely to drop by gravity, the filter cloth driving means in a conventional simultaneous plate separation type filter press in which a cake removing means of the filter cloth travelling type is employed is too costly for such means. It is also pointed out that a conventional sequential plate separation type filter press in which a cake removing means of the filter cloth jolting type is employed is very inefficient in that an excessively long period of time is required for removal of cakes that can be readily knocked out, as compared with the time required for filtering operation.